Local alarm circuit for burglar alarm systems



Feb. 17, 1959 LE ROY c. SPENARD 2, 7

LOCAL ALARM CIRCUIT FOR BURGLAR ALARM SYSTEMS Filed 001;. 21, 1954 1 1 l1 i l I g Q 0 m9 I 1 l A a, f 1 1 s s a 3N! w 8 1 :0 ll L s-\ m S Nr*------,-- I X. N N

N I Niki I i w 9 1 i 1 N h- O 1 2 Q I i? 4% m I L J INVENTOR.

Le gy C. Sp enard United States Patent LOCAL ALARM 'CIRCUIT FOR BURGLARALARM SYSTEMS Le Roy C. Spenard, Port Washington, N. Y., assignor toHolmes Electric Protective Company, New York, N. Y., a corporation ofNew York Application October 21, 1954, Serial No. 463,733

1 Claim. (Cl. 340-276) The present invention relates to a local alarmcircuit for burglar alarm systems and in particular to a local alarmcircuit which is arranged in such a way that the local alarm is soundedif an attempt is made to disable it.

In many local alarm circuits the alarm is actuated directly in response.to the closing of a switch which is activated in response to theentrance of an intruder. In such an arrangement the local alarm can berendered inoperative by simply cutting the lines which come from theswitch into the alarm box.

It is an object of the present invention to provide a local alarmcircuit for a burglar alarm system in which the alarm is permanentlyenergized when the leads into the alarm box are cut.

It is another object of the present invention to provide a local alarmcircuit for a burglar alarm system which may be readily added to systemswhich are already installed.

Yet another object of the present invention is to provide a local alarmcircuit for a burglar alarm system in which it is extremely diificult todisable the local alarm circuit.

A further object of the present invention is to pro vide in anarrangement wherein the local alarm is housed separately from thecircuit responding to the condition to be sensed and conductorsinterconnect the separately housed components improved circuit meanswhereby cutting of any of the interconnecting conductors causesactuation of the alarm.

A still further object of the present invention is to provide in anarrangement wherein the local alarm is housed separately from thecircuit responding to the condition to be sensed and conductorsinterconnect the separately housed components, improved circuit meanswhereby cutting of any or all of the interconnecting conductors causesactuation of the alarm.

Various other objects and advantages will become apparent from thedetailed description to follow.

Referring to the drawing one terminal of a condition responsive normallyopen sensing switch 2 is connected to the negative terminal of thebattery 4 the positive terminal of which is grounded. The other terminalof the switch 2 is connected to the relay 6 over the line 8. The otherside of the relay is connected toground over line 10. The front contact12 of the relay 6 is connected to line 8 and is positioned to be engagedby the armature 14. The armature 14 is connected through the switch 16to the negative terminal of the battery 18, the positive terminal ofwhich is grounded. The contact 12 and armature 14 are shunted by thecapacitor 20. The front contact 22 of the relay 6 is connected over line24 to the terminal 26. The armature 28 of the relay 6 is connected toground by line 10. The components thus far described are enclosed orhoused within a metal case which is designated by the dashed line 30.The metal box prevents tampering with any of the units enclosed thereinand if an attempt is made to open this box the overall system will causethe switch 2 to be closed.

The terminal 26 is connected over the lines 32 and 34 to the terminals36 and 38 which are enclosed within the alarm box. The alarm box isindicated by the dashed lines 40. The line 10 is connected to theterminal 42 which in turn is connected over lines 44 and 45 to theterminal 46 and one line of alarm relay 48 also within the alarm box.The lines 32, 34, 44 and 45 are enclosed within a metal pipe forpurposes of protection. The terminal 36 is connected to the other linesof the relay 48. The armature 52 of the relay 48 is connected to theline 50. The terminal 46 is connected to the battery 54, and theterminal 38 is connected through the resistor 56 to the other end of thebattery 54. The bell 58 has one terminal connected over the line 60 tothe battery 54 and the other terminal is connected over the line 62 tothe contact 64 of the relay 48. The armature 52 engages the dead contact66 of the relay 48 when the relay is energized.

The drawing shows the entire circiut in its standby or normal condition;this is when the switch 2 is in its normally open condition. The relay48 is energized by the battery 54 and the armature 52 is engaging thedead contact 66. The current required to maintain the relay 48 energizedis about 2 to 3 milliamperes which represents a very small drain on thebattery.

When the condition responsive sensing switch 2 is actuated in responseto the entrance of an intruder into the protected enclosure the relay 6is energized by the battery 4. Energization of this relay causes thearmature 14 to engage contact 12 thereby connecting the relay across thebattery 18. Therefore, if the switch 2 is subsequently opened the relay6 will remain energized. The switch 16 is included in the circuit sothat the hold ing circuit may be opened by authorized personnel. If thearmature 14 is caused to vibrate the capacitor 20 will supply energy tothe relay during the brief intervals when the armature 14 is disengagedfrom the contact 12.

In addition to actuation of the armature 14, the relay 6 causes thearmature 28 to engage the contact 22. This applies a short circuitacross the alarm relay 48 causing it to be deenergized. This shortingcircuit begins at the terminal 26 and is completed over line 24, contact22, armature 28, line 10, terminal 42 and line 45. When this occurs thearmature 52 is dropped and engages the contact 64 thereby completing thecircuit of the bell 58 from the battery 54, line 60, the bell 58, line62, contact 64, armature 52, line 59, and terminal 46. This causes thebell to ring.

The resistor 56 prevents a dead short from being thrown across thebattery 54 when the armature 28 engages the contact 22.

It can be seen from the above description that the lines or conductorsbetween the box 30 and the alarm box 40 are the lines 32, 34, 44 and 45.If any of these lines is cut in an attempt to silence the bell 58, therelay 48 is permanently cut oil from the battery 54, which will maintainthe relay deenergized. As previously pointed out when the relay 48 isdeenergized the bell 50 will ring. Therefore, any attempt to render thebell inoperative by cutting the lines into the alarm box 40 will merelyresult in the actuation of the local alarm.

The lines 32 and 34 may be considered as an elongated open-sided loop onone side of the relay 48 and the lines 44 and 45 may be considered as anelongated open-sided loop on the other side of the relay 48. The opensides of the two elongated loops connect, respectively, one terminal ofrelay 48 with one terminal of battery 54 and the other terminal of relay48 with the nee e other terminal of battery 54. 'Also, the connectionsat 26 and 42 may be considered as being made at the bight portions ofthe loops. I I I I I As this invention may be embodied in several'formswithout departing from the spirit or essential characteristics thereof,the present embodiment is therefore illustrative and not restrictive,since the scope of the invention is defined by the appended claimsrather than by the description preceding them, and all changes that fallWithin the metes and bounds of the claims or that form their functionalas well as conjointly cooperative equivalents, are therefore intended tobe embraced by I I the claim.

What is claimed is: I I I An alarm circuit including: a first circuitlocated in a first housing and having in series an alarm relay and abattery which normally energizes said relay and holds the armatureofsaid relay in a first position; means re-" sponsive to the movement ofsaid armature to a second position to give an alarm signal; a normallyopen switch closing in-response to a condition to be sensed; the saidfirst circuit including a first elongated open-sided loop in thelinebetween oneterrninal of the relay and one terminal of the batteryand a second elongated opensided loop in the line between the otherterminal of the relay and the other terminal of the battery, theterminals of the said normally open switch being connected,respectively, to the bight portions of each loop; the saidnorrnallyaopen :switchand its connection to the bight References Citedin the file of this patent UNITED STATES PATENTS 1,901,628 Brainard Mar.14, 1933 2,019,320 Runner Oct. 29, 1935 r 2,101,049 Clingerman Dec. 7,1937 2,686,909 Poulson Aug. 17, 1954

